This invention relates to a rotatable coupling system primarily used in heart catheterization, and method of operating the same.
Catheterization procedure requires that a catheter be first connected to a fluid pressure source and then threaded through a blood vessel in the patient's arm and into the heart. The catheter must remain connected to the source of fluid to avoid exposure of the antiseptic catheter to bacteria during the insertion process. The path from the blood vessel to the heart is tortuous and requires the catheter to rotate while remaining connected to the fluid source. To allow for this rotation, rotatable couplings or rotators are used.
High pressure injectors used in heart catheterization require the rotator to withstand fluid pressures in the 650-700 psi range without leaking or separating. Existing high pressure rotators are made with three pieces that are ultrasonically welded together and bonded to a manifold. FIG. 6 shows a cross section of a three piece rotator bonded to a manifold. The first outer piece 40 is ultrasonically welded at weld joint 44 to the second outer piece 41 to retain the inner piece 42 and O-ring 43. The first outer piece 40 has a standard male Luer 48 formed therein for locking with a female standard Luer member on the end of a catheter. One end of the inner piece 42 is bonded at bond joint 45 to the stem 46 of the manifold 47.
One problem with the three-piece rotator assembly is that it requires a bonding joint 45 to connect the assembly to the manifold. First, the bonding joint creates a visual obstruction. The bonding process leaves an approximately 1/4 inch blind spot in the coupling which may prevent recognition of air bubbles formed in the fluid within the coupling. Second, the bonded connection may be a source of leaks. Third, the bonding process may create bonded bubbles which are actually bonded into the joint, but give the appearance of air bubbles in the fluid pathway. Fourth, the bonding process may leave a small bonding gap 49 between the rotator assembly and the manifold, which provides an area for air bubbles to be entrapped. Fifth, the bonding process requires the use of Methylene Chloride (Dichloromethane) which has been listed as a hazardous chemical by O.S.H.A.
A second problem with the three-piece rotator assembly is the requirement that the two outer pieces be ultrasonically welded. The weld joint may become a failure point during high pressure fluid flow.
A third problem with the three-piece rotator assembly is that the fluid path is composed of a series of varying diameters which allow areas for bubble entrapment and create turbulence in the fluid pathway.
A fourth problem with the three-piece rotator assembly is the significant labor required in the assembly operation. First, the three pieces or subassemblies must be manufactured. Next, the two outer subassemblies must be ultrasonically welded together and bonded to the manifold.